Tending to expand for a while – a year (8)
I believe the answer is:
stretchy
'tending to expand' is the definition.
I can't judge whether this definition defines the answer.
'a while a year' is the wordplay.
'a while' becomes 'stretch' (I've seen this before).
'a year' becomes 'y'.
'stretch'+'y'='STRETCHY'
'for' is the link.
Can you help me to learn more?
(Other definitions for stretchy that I've seen before include "Elastic" , "Of variable length, perhaps" , "Flexible" .)