Cricketer seen if climbing tree (7)
I believe the answer is:
fielder
'cricketer' is the definition.
(I know that fielder is a type of cricketer)
'if climbing tree' is the wordplay.
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'tree' becomes 'elder' (elder is a kind of tree).
'if' written backwards gives 'fi'.
'fi'+'elder'='FIELDER'
'seen' is the link.
(Other definitions for fielder that I've seen before include "one in gully, perhaps" , "Slip, perhaps" , "Cricketing slip, say?" , "Cricketer not on batting side" , "cover, perhaps" .)