To cut the grass outside the pub is not a big thing (6)
I believe the answer is:
minnow
'not a big thing' is the definition.
I can't tell whether this defines the answer.
'to cut the grass outside the pub' is the wordplay.
'to cut the grass' becomes 'mow' (I've seen this in another clue).
'outside' is an insertion indicator (some letters go outside others).
'the pub' becomes 'inn' (an inn is a type of pub).
'mow' enclosing 'inn' is 'MINNOW'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for minnow that I've seen before include "Small fry" , "unimportant person" , "he's unimportant" , "Very little fish" , "Tiny freshwater fish" .)