Thus the thrifty resort to make a phone call (7)
I believe the answer is:
sparing
'thus the thrifty' is the definition.
I can't judge whether this defines the answer.
'resort to make a phone call' is the wordplay.
I cannot really understand how this works, but
'resort' could be 'spa' (spa is a kind of resort) and 'spa' is found in the answer.
'phone' could be 'ring' (to ring on the phone) and 'ring' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sparing that I've seen before include "Economical; having mercy" , "Thrifty" , "Scanty - merciful" , "mean" , "Moderate, economical" .)