At first girl simply removed item of clothing (7)
I believe the answer is:
gymslip
'item of clothing' is the definition.
'at first girl simply removed' is the wordplay.
'at first' says to take the initial letters.
'removed' indicates anagramming the letters (moved again).
The first letter of 'girl' is 'g'.
'simply' is an anagram of 'ymslip'.
'g'+'ymslip'='GYMSLIP'
(Other definitions for gymslip that I've seen before include "Pre-Lycra exercise wear" , "old girl's uniform" , "schoolgirl attire" , "Former schoolgirl's wear" , "Schoolgirl's PE uniform" .)