Garment covering one that's more nervous (7)
I believe the answer is:
jumpier
'more nervous' is the definition.
('jumpy' can be a synonym of 'nervous')
'garment covering one' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'garment' could be 'jumper' (jumper is a kind of garment) and 'jumper' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'that's' is the link.
Can you help me to learn more?
(Another definition for jumpier that I've seen is " more nervous".)