Slip home when picked up (5)
I believe the answer is:
gaffe
'slip' is the definition.
(both can mean an error or blunder)
'home when picked up' is the wordplay.
'home' becomes 'gaff' (I've seen this before).
'when picked up' indicates a 'sounds like' (homophone) clue (pick up can mean to hear).
'gaff' sounds like 'GAFFE'.
(Other definitions for gaffe that I've seen before include "A foolish error" , "A blunder, faux pas" , "indiscreet remark" , "slip" , "bad mistake" .)