Body beginning to glaciate in Antarctica? (10)
I believe the answer is:
contingent
'body' is the definition.
(thesaurus)
'beginning to glaciate in antarctica?' is the wordplay.
'beginning to' indicates taking the first letters.
'in' is an insertion indicator.
'antarctica?' becomes 'continent' (antarctica is a kind of continent).
The first letter of 'glaciate' is 'g'.
'g' going inside 'continent' is 'CONTINGENT'.
(Other definitions for contingent that I've seen before include "Some soldiers" , "Depending (on) - part of military force" , "Quota of troops" , "Subject to chance" , "uncertain" .)