Heard you spilled wine over skinhead with rash (6)
I believe the answer is:
Here is my best explanation:
'rash' is the definition.
'heard you spilled wine over skinhead' is the subsidiary indication.
'heard' indicates a 'sounds like' (homophone) clue.
'spilled' indicates anagramming the letters.
'over' means one lot of letters goes inside another.
'skinhead' becomes 's' (head letter of 'skin').
'you' is a homophone of 'u'.
'wine' with letters rearranged gives 'nwie'.
'nwie' placed around 's' is 'nwise'.
'with' is the link.
(Other definitions for unwise that I've seen before include "Injudicious", "Not sensible, foolish", "Lacking sound judgement, maybe foolish", "Foolish", "Not sensible or prudent" and "Foolhardy".)