Popular Democrat outside certain to be covered (7)
I believe the answer is:
insured
'be covered' is the definition.
(covered by insurance)
'popular democrat outside certain' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'democrat' becomes 'd'.
'outside' indicates putting letters inside (some letters go outside others).
'certain' becomes 'sure' (synonyms).
'in'+'d'='ind'
'ind' enclosing 'sure' is 'INSURED'.
'to' acts as a link.
(Other definitions for insured that I've seen before include "Covered for loss" , "Covered against accident" , "Financially protected" , "Covered for burglary?" , "Covered for losses" .)