Really full wolves maybe to have misgivings we hear (6,3)
I believe the answer is:
packed out
'really full' is the definition.
(as in a packed out theatre)
'wolves maybe to have misgivings we hear' is the wordplay.
'wolves maybe' becomes 'pack' (pack of wolves).
'to have' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'misgivings' becomes 'doubt' (I've seen this in another clue).
'we hear' shows a homophone (sound like).
'doubt' sounds like 'dout'.
'pack'+'e'+'dout'='PACKED OUT'
(Another definition for packed out that I've seen is " (Hall) full to capacity".)