Foolish talk — see bishop foam (7)
I believe the answer is:
blather
'foolish talk' is the definition.
(I've seen this in another clue)
'bishop foam' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'foam' becomes 'lather' (lathering is a kind of foaming).
'b'+'lather'='BLATHER'
'see' is the link.
(Other definitions for blather that I've seen before include "Rubbishy old talk, foolish chat" , "(Talk) gibberish" , "Long-winded talk with no substance" , "Palaver, prattle" , "Foolish chatter, just oul' talk" .)