After parking trouble, girls mostly sleep on this (9)
I believe the answer is:
paillasse
'sleep on this' is the definition.
The definition suggests a singular noun which matches the answer.
'after parking trouble girls mostly' is the wordplay.
'after' means one lot of letters go next to another.
'parking' becomes 'p' (abbreviation on road signs).
'trouble' becomes 'ail' (synonyms).
'girls' becomes 'lasses' (lass can informally mean a girl).
'mostly' means to remove the last letter.
'lasses' with its last letter taken away is 'lasse'.
'p' next to 'ail' is 'pail'.
'pail'+'lasse'='PAILLASSE'
Can you help me to learn more?
(Other definitions for paillasse that I've seen before include "Bedding" , "Maybe sleep on it" , "straw bed" .)