Little boat's heading into cove (4)
I believe the answer is:
baby
'little' is the definition.
(thesaurus)
'boat's heading into cove' is the wordplay.
'heading' suggests taking the first letters (head could mean the top letter).
'into' is an insertion indicator.
'cove' becomes 'bay' (both can mean a coastal inlet).
The first letter of 'boats' is 'b'.
'b' going within 'bay' is 'BABY'.
(Other definitions for baby that I've seen before include "Comparatively small" , "Mollycoddle" , "Girlfriend" , "Infancy" , "Very young person" .)