Tense about a certain term of endearment (8)
I believe the answer is:
treasure
'term of endearment' is the definition.
'tense about a certain' is the wordplay.
'tense' becomes 't' (abbreviation used in many dictionaries).
'about' becomes 'rea' (I've seen this in other clues**).
'a certain' becomes 'sure' (I've seen this before).
't'+'rea'+'sure'='TREASURE'
(Other definitions for treasure that I've seen before include "Valued friend" , "Valued possession, buried perhaps" , "Quantity of precious objects" , "' - - Island' novel" , "Cherish like heap of valuables" .)