Clue: Speciality of Agen once, long fed on contact sport? (6)
Answer: PRUINE
Explanation: Definition: Speciality of Agen once
**PINE** ("long") *fed on* **RU** (rugby union, so "contact sport") 
"Pruine" *is an old word for* "prune"*, a foodstuff for which Agen is particularly noted.