A great deal brings fellow into garret (4)
I believe the answer is:
loft
'garret' is the definition.
(synonyms)
'a great deal brings fellow' is the wordplay.
I cannot really understand how this works, but
'fellow' could be 'f' (abbreviation - of a society etc.) and 'f' is found in the answer.
'deal' could be 'lot' (synonyms) and 'lot' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'into' is the link.
Can you help me to learn more?
(Other definitions for loft that I've seen before include "Attic" , "Sky" , "Kick high in the air" , "Roof space area" , "Throw up; pigeon house" .)