Fits maps, folded into spacious jacket (6)
I believe the answer is:
spasms
'fits' is the definition.
(spasm can mean a fit)
'maps folded into spacious jacket' is the wordplay.
'folded' indicates an anagram.
'into' is an insertion indicator.
'jacket' means to remove the middle letters (the letters worn by the word as a 'jacket' are use).
'spacious' with its middle removed is 'ss'.
'maps' anagrammed gives 'pasm'.
'pasm' inserted inside 'ss' is 'SPASMS'.
(Other definitions for spasms that I've seen before include "Tics" , "Involuntary convulsive movements" , "Strong involuntary muscular contractions" , "spells" , "attacks" .)