A man acknowledging a message (5)
I believe the answer is:
roger
'a message' is the definition.
(I know that roger is a type of message)
'a man acknowledging' is the wordplay.
I cannot quite understand how this works, but
'man' could be 'rog' and 'rog' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for roger that I've seen before include "Ackroyd" , "Boy's name - received and understood" , "- - Moore (007)" , "Expression of agreement" , "man, > I understand" .)