Pick up king, then knight (5)
I believe the answer is:
learn
'pick up' is the definition.
('learn' can be a synonym of 'pick up')
'king then knight' is the wordplay.
'king' becomes 'lear' (I've seen this before).
'then' is a charade indicator (letters next to each other).
'knight' becomes 'n' (chess).
'lear'+'n'='LEARN'
(Other definitions for learn that I've seen before include "Master" , "Find out - assimilate facts" , "Come to know" , "Pick up" , "Renal (anag)" .)