Thanks given upon opening of splendid gifts (7)
I believe the answer is:
talents
'gifts' is the definition.
(I know this)
'thanks given upon opening of splendid' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'given' becomes 'lent' (lending is a kind of giving).
'upon' says to put letters next to each other.
'opening of' suggests taking the first letters.
The first letter of 'splendid' is 's'.
'ta'+'lent'+'s'='TALENTS'
(Other definitions for talents that I've seen before include "Natural aptitudes" , "Special aptitudes" , "endowments" , "Last ten (anag.)" , "Gifts, abilities" .)