Wrongly target a sporting event — at Henley, perhaps? (7)
I believe the answer is:
regatta
'event at henley perhaps?' is the definition.
(as in the Henley Royal Regatta)
'wrongly target a sporting' is the wordplay.
'wrongly' indicates anagramming the letters (I've seen this in other clues).
'sporting' means one lot of letters goes inside another (inserted letters wear or 'sport' others).
'target' with letters rearranged gives 'regtta'.
'regtta' placed around 'a' is 'REGATTA'.
(Other definitions for regatta that I've seen before include "race on the river" , "Yachting festival" , "Sporting event with boat or yacht races" , "competition between banks" , "Event for craft" .)