Terrible strain, meeting a Russian ruler (7)
I believe the answer is:
tsarina
'russian ruler' is the definition.
(female tsar)
'terrible strain meeting a' is the wordplay.
'terrible' is an anagram indicator.
'meeting' means one lot of letters go next to another.
'strain' anagrammed gives 'tsarin'.
'tsarin'+'a'='TSARINA'
(Other definitions for tsarina that I've seen before include "Catherine, say" , "Monarch" , "Wife of an old Russian emperor" , "titled lady" , "lady of some importance" .)