Caught with partner in plant (6)
I believe the answer is:
clover
'plant' is the definition.
(clover is a kind of plant)
'caught with partner' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'with' means one lot of letters go next to another.
'partner' becomes 'lover' (I've seen this before).
'c'+'lover'='CLOVER'
'in' is the link.
(Other definitions for clover that I've seen before include "Common trefoil" , "Weed or forage plant (which it's good to be in)" , "Pea family plant with three-lobed leaves" , "A four-leafed one is lucky" , "in which we can live luxuriously" .)