Clue: Love getting stuck into a Pimm's, stirred, having no head for Buck's fizz (6)
Answer: MIMOSA
Explanation: Definition: Buck's fizz
**O** (love, in tennis) *getting stuck into* ***(a imms)** [anag:*stirred*] where IMMS is (p)IMMS [*having no head*] 
*Champagne and orange juice is known as Buck's Fizz in the UK and as a mimosa in the US.