Get ready to shoot a picture, opening mostly depicting crow (4,1,6,3)
I believe the answer is:
cock a doodle doo
'crow' is the definition.
(thesaurus)
'get ready to shoot a picture opening mostly' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
'get ready to shoot' could be 'cock' (I've seen this before) and 'cock' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'depicting' is the link.
Can you help me to learn more?
(Other definitions for cock a doodle doo that I've seen before include "wake-up call" , "Early morning call" .)