Retro funk's back -- my kind of music (4)
I believe the answer is:
rock
'kind of music' is the definition.
(I know that rock is a type of genre)
'retro funk's back my' is the wordplay.
'retro' is a reversal indicator (retro is Latin for 'backwards').
'back' says to take the final letters (the letter at the back).
'my' becomes 'cor' (both are expressions of surprise).
The final letter of 'funk' is 'k'.
'k'+'cor'='kcor'
'kcor' in reverse letter order is 'ROCK'.
(Other definitions for rock that I've seen before include "Hard stone or lively music" , "Large stone - type of music" , "Boulder; music" , "Music; diamond" , "Boulder - oscillate - sweetmeat" .)