Mo in second, yet at end clutching bronze (7)
I believe the answer is:
instant
'mo' is the definition.
(both can mean a short period of time)
'in second yet at end clutching bronze' is the wordplay.
'second yet' becomes 's' (common abbreviation. I am not sure about the 'yet' bit.).
'end' says to take the final letters.
'clutching' is an insertion indicator.
'bronze' becomes 'tan' (both can mean to get a sun tan).
The final letter of 'at' is 't'.
's'+'t'='st'
'st' enclosing 'tan' is 'stant'.
'in'+'stant'='INSTANT'
Can you help me to learn more?
(Other definitions for instant that I've seen before include "Without delay - short time" , "A second - coffee, maybe" , "Immediate; flash" , "Precise moment" , "Mo" .)