Taking the trouble to be thrifty (7)
I believe the answer is:
careful
'thrifty' is the definition.
(synonyms)
'taking the trouble' is the wordplay.
I cannot quite see how this works, but
'trouble' could be 'care' and 'care' is present in the answer.
The remaining letters 'ful' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for careful that I've seen before include "Thorough" , "Painstaking" , "Guarded" , "Thrifty" , "Attentive" .)