Factory initially releasing extremely showy clothing (8)
I believe the answer is:
refinery
'factory' is the definition.
(thesaurus)
'initially releasing extremely showy clothing' is the wordplay.
'initially' indicates taking the first letters.
'showy clothing' becomes 'finery' (finery can mean fancy or ceremonial clothing).
The first letters of 'releasing extremely' is 're'.
're'+'finery'='REFINERY'
(Other definitions for refinery that I've seen before include "Industrial processing plant (for, eg, oil)" , "Where oil is processed" , "Purification plant" , "Industrial installation where a substance is purified" , "Chemical plant" .)