Shout to bishop on old ship (4)
I believe the answer is:
bark
'shout' is the definition.
(thesaurus)
'bishop on old ship' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'old ship' becomes 'ark' (as in Noah's ark).
'b'+'ark'='BARK'
'to' acts as a link.
(Other definitions for bark that I've seen before include "Tree's outer layer" , "give sharp cry" , "Shout gruffly; part of tree" , "old vessel" , "Sound from animal < having part of tree" .)