'Dunno ... he maybe on the end of ward C' (3,7)
I believe the answer is:
one hundred
'c' is the definition.
(synonyms)
'dunno he maybe on the end of ward' is the wordplay.
'maybe' is an anagram indicator.
'on' becomes 're' ('on' can be mean 'with reference to').
'the end of' indicates one should take the final letters.
The last letter of 'ward' is 'd'.
'dunno'+'he'='dunnohe'
'dunnohe' anagrammed gives 'onehund'.
'onehund'+'re'+'d'='ONE HUNDRED'
(Other definitions for one hundred that I've seen before include "C" , "It may be Frimley Green's call" .)