Great tennis playing by the English (7)
I believe the answer is:
intense
'great' is the definition.
(I've seen this before)
'tennis playing by the english' is the wordplay.
'playing' indicates an anagram.
'by' is a charade indicator (letters next to each other).
'the english' becomes 'e' (abbreviation).
'tennis' with letters rearranged gives 'intens'.
'intens'+'e'='INTENSE'
(Other definitions for intense that I've seen before include "'Acute, extreme (7)'" , "Acute, concentrated" , "Forceful, concentrated" , "Fierce - deep" , "Acute, exteme" .)