Uninteresting doctor meets sailor (4)
I believe the answer is:
drab
'uninteresting' is the definition.
(similar in meaning)
'doctor meets sailor' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'meets' says to put letters next to each other.
'sailor' becomes 'ab' (abbreviation for able seaman).
'dr'+'ab'='DRAB'
(Other definitions for drab that I've seen before include "Dull and monotonous" , "woman with slatternly habits" , "Drearily dull; slattern" , "Lacking brightness or colour" , "Dowdy" .)