Dubious description of element of rally? (10)
I believe the answer is:
backhanded
I believe this is a double definition.
'dubious' is the first definition.
(as in a backhanded compliment)
'description of element of rally?' is the second definition.
(as in a tennis rally)
(Other definitions for backhanded that I've seen before include "Some tennis shots are" , "Ambiguously flattering remark" , "not straight" .)