Exposed, king in small valley, climbing (5)
I believe the answer is:
naked
'exposed' is the definition.
(I've seen this before)
'king in small valley climbing' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'in' indicates putting letters inside.
'small valley' becomes 'dean' (a dean is a valley).
'climbing' says the letters should be written backwards (in a down clue, letters climb up).
'k' inserted into 'dean' is 'dekan'.
'dekan' written backwards gives 'NAKED'.
(Other definitions for naked that I've seen before include "In one's birthday suit" , "In the altogether" , "being exposed" , "Undressed" , "Without protection" .)