Stand outside quarters in a state of the jitters (5)
I believe the answer is:
tense
'state of the jitters' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?
'stand outside quarters' is the wordplay.
'stand' becomes 'tee' (I've seen this before).
'outside' means one lot of letters goes inside another (some letters go outside others).
'quarters' becomes 'ns' ().
'tee' placed around 'ns' is 'TENSE'.
'in a' acts as a link.
Can you help me to learn more?
(Other definitions for tense that I've seen before include "contract" , "Rigid, or grammatical time" , "Stretched tightly, unable to relax" , "Unrelaxed; form of verb" , "past, say" .)