It grows disheartened when there's a shifty banker around (7)
I believe the answer is:
bracken
'it grows disheartened when' is the definition.
The definition suggests a singular noun which matches the answer.
'a shifty banker around' is the wordplay.
'a shifty' indicates anagramming the letters.
'around' becomes 'c' (abbreviation for 'circa').
'banker'+'c'='bankerc'
'bankerc' with letters rearranged gives 'BRACKEN'.
'there's' acts as a link.
Can you help me to learn more?
(Other definitions for bracken that I've seen before include "Tall fern" , "Plant" , "British moorland fern" , "Large coarse fern" , "Fern on the hillside" .)