With Mike contributing, sets about puzzle (5)
I believe the answer is:
stump
'puzzle' is the definition.
(I know that stump is a more specific form of the action puzzle)
'with mike contributing sets about' is the wordplay.
'with' is an insertion indicator.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'contributing sets' becomes 'puts' ('put' can be a synonym of 'set'. I am not sure about the 'contributing' bit.).
'about' is a reversal indicator.
'm' placed inside 'puts' is 'pmuts'.
'pmuts' written backwards gives 'STUMP'.
Can you help me to learn more?
(Other definitions for stump that I've seen before include "Wicket upright; greatly puzzle" , "an axeman would leave behind" , "Flummox" , "Wicket part - dumbfound" , "defeat" .)