Joy of English language once gripping head of Oundle (7)
I believe the answer is:
elation
'joy' is the definition.
(elation is a kind of joy)
'english language once gripping head of oundle' is the wordplay.
'english' becomes 'E' (abbreviation as in OED).
'language once' becomes 'Latin' (ancient language).
'gripping' indicates putting letters inside (inserted letters are gripped).
'head of' says to take the initial letters.
The first letter of 'oundle' is 'o'.
'latin' going around 'o' is 'lation'.
'e'+'lation'='ELATION'
'of' is the link.
(Other definitions for elation that I've seen before include "Feeling of joy and pride" , "There's great joy" , "It's a great feeling!" , "'High spirits, exhilaration (7)'" , "Feeling of joy for it alone" .)