Recent advances in DNA data storage and racetrack memory have attracted renewed attention towards deletion, insertion and substitution correcting codes. Compared to codes aimed at correcting either substitution errors or deletion and insertion (indel) errors, the understanding of codes that correct combinations of substitution and indel errors lags behind. In this paper, we focus on the maximal size of q-ary t-indel s-substitution correcting codes. In particular, our main contribution is a Gilbert-Varshamov inspired lower bound on this size. Moreover, we study the asymptotic behaviour of this bound.