Covert resistance fostered by Tory minister (5)
I believe the answer is:
grove
'covert' is the definition.
(covert can mean a grove of trees)
'resistance fostered by tory minister' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'fostered by' is an insertion indicator (inserted letters are housed or fostered).
'tory minister' becomes 'Gove' (Conservative politician Michael Gove).
'r' inserted within 'gove' is 'GROVE'.
(Other definitions for grove that I've seen before include "Wood of small size" , "Small growth of trees" , "Hurst" , "Small woodland" , "Writer on music" .)