Prime order gets one large risk (7)
I believe the answer is:
imperil
'risk' is the definition.
(I've seen this in another clue)
'prime order gets one large' is the wordplay.
'order' indicates an anagram.
'gets' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'large' becomes 'L' (eg in clothes sizes).
'prime' is an anagram of 'mperi'.
'i'+'l'='il'
'mperi' going within 'il' is 'IMPERIL'.
(Other definitions for imperil that I've seen before include "Put in danger" , "Jeopardize" , "Threaten, jeopardise" , "Put at risk" , "put at hazard" .)