Expand bog with a dry filler (6)
I believe the answer is:
fatten
'expand' is the definition.
(thesaurus)
'bog with a dry filler' is the wordplay.
I cannot really understand how this works, but
'a' is present in the answer.
'dry' could be 'tt' (abbreviation for teetotal) and 'tt' is found in the answer.
'bog' could be 'fen' (I've seen this in another clue) and 'fen' is found in the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for fatten that I've seen before include "Make plump" , "Make chubbier" .)