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Open star clusters older than ~ 1 Gyr are rare in the inner Galactic disc.Still, they are objects that hold crucial information for probing the chemicalevolution of these regions of the Milky Way. We aim at increasing the number ofold open clusters in the inner disc for which high-resolution metal abundancesare available. Here we report on NGC 4337, which was recently discovered to bean old, inner disc open cluster. We present the very first high-resolutionspectroscopy of seven clump stars that are all cluster members. We performed adetailed abundance analysis for them. We find that NGC 4337 is marginally moremetal-rich than the Sun, with [Fe/H]=+0.12$\pm$0.05. The abundance ratios of$\alpha$-elements are generally solar. At odds with recent studies onintermediate-age and old open clusters in the Galactic disc, Ba isunder-abundant in NGC 4337 compared with the Sun. Our analysis of the iron-peakelements (Cr and Ni) does not reveal anything anomalous. Based on theseresults, we estimate the cluster age to be 1.6$^{+0.1}_{-0.1}$ Gyr, and derivea reddening E(B-V)=0.23$\pm$0.05, and an apparent distance modulus$(m-M)_{V}=12.80\pm0.15$. Its distance to the Galactic centre is 7.6 kpc. Withthis distance and metallicity, NGC 4337 fits the metallicity gradient for theinner Galactic disc fairly well. The age and metallicity we measured make NGC4337 a twin of the well-known old open cluster NGC 752. The red clumps of thesetwo clusters bear an amazing resemblance. But the main sequence of NGC 752 issignificantly more depleted in stars than that of NGC 4337. This would meanthat NGC 752 is in a much more advanced dynamical stage, being on the verge ofdissolving into the general Galactic field. Our results make NGC 4337 anextremely interesting object for further studies of stellar evolution in thecritical turn-off mass range 1.1-1.4 solar masses.

Abundance analysis of red clump stars in the old, inner disc, open cluster NGC 4337: a twin of NGC 752?