Split force is no problem (7)
I believe the answer is:
fissure
'split' is the definition.
(thesaurus)
'force is no problem' is the wordplay.
'force' becomes 'f' (abbreviation in physics e.g. f=ma).
'no problem' becomes 'sure' (I've seen this in another clue).
'f'+'is'+'sure'='FISSURE'
(Other definitions for fissure that I've seen before include "Long, narrow opening" , "Crevice" , "Split, crack" , "Split - cleavage" , "Deep crack in rock" .)