Checked fit (of clothes) and changed into red (5,2)
I believe the answer is:
tried on
'checked fit of clothes' is the definition.
(as in trying on clothes)
'changed into red' is the wordplay.
'changed' indicates an anagram.
'into'+'red'='intored'
'intored' with letters rearranged gives 'TRIED ON'.
'and' acts as a link.
(Other definitions for tried on that I've seen before include "Donned a garment to see if it suited" , "Tested the fit of (a garment)" , "tested for suitability" , "Checked shirt perhaps" .)