Parliament has film showing way to slow growth (4,5)
I believe the answer is:
diet sheet
'way to slow growth' is the definition.
I know nothing about this answer so I can't tell whether this works.
'parliament has film' is the wordplay.
'parliament' becomes 'diet' (I've seen this before).
'has' says to put letters next to each other.
'film' becomes 'sheet' (I've seen this before).
'diet'+'sheet'='DIET SHEET'
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for diet sheet that I've seen before include "List of courses permitted" , "List of slimming foods" , "List of permitted foods" .)