Not completely understand every cry of disapproval (7)

I believe the answer is:

catcall

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'cry of disapproval' is the definition.
'catcall' can be an answer for 'disapproval' (I have seen 'Express disapproval' mean 'catcall' so perhaps 'disapproval' could also mean 'catcall'). I'm not certain of the 'cry of' bit.

'not completely understand every' is the wordplay.
'not completely' means to remove the last letter (the word is incomplete).
'understand' becomes 'catch' (I've seen this before).
'every' becomes 'all' (similar in meaning).
'catch' with its last letter taken away is 'catc'.
'catc'+'all'='CATCALL'

Can you help me to learn more?

(Other definitions for catcall that I've seen before include "Boo" , "Derisive cry" , "disapproving expression" , "Audibly disapprove" , "Barracking" .)

I've seen this clue in The Telegraph.

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