Vegetable left in coach for insect (4,6)
I believe the answer is:
stag beetle
'insect' is the definition.
(stag beetle is a kind of insect)
'vegetable left in coach' is the wordplay.
'vegetable' becomes 'beet' (beet is a kind of vegetable).
'left' becomes 'l' (common abbreviation).
'in' means one lot of letters goes inside another.
'coach' becomes 'stage-' (stagecoach).
'beet'+'l'='beetl'
'beetl' going within 'stage' is 'STAG-BEETLE'.
'for' is the link.
(Other definitions for stag beetle that I've seen before include "something some folk find creepy" , "Insect with antler-like jaws" , "Large insect with branched mandibles" , "Six-footer" , "Horny little creature" .)