Submissive female catches chill, periodically (6)
I believe the answer is:
docile
'submissive' is the definition.
(I've seen this before)
'female catches chill periodically' is the wordplay.
'female' becomes 'doe' (female deer).
'catches' means one lot of letters goes inside another.
'periodically' indicates alternate letters (letters must be selected 'every so often').
The alternating letters of 'chill' are 'cil'.
'doe' enclosing 'cil' is 'DOCILE'.
(Other definitions for docile that I've seen before include "Meek and biddable" , "Tractable and pliant" , "easy to manage" , "Gentle, tame" , "Coiled in obedient way" .)