They deliver MP's note perhaps (7)
I believe the answer is:
postmen
'they deliver' is the definition.
(I've seen this before)
'mp's note perhaps' is the wordplay.
'perhaps' indicates an anagram.
'mps'+'note'='mpsnote'
'mpsnote' anagrammed gives 'POSTMEN'.
(Other definitions for postmen that I've seen before include "They deliver mail" , "Male mail carriers" , "Mail deliverers" .)