Reasonable skirts silver and trendy (3,3,4)
I believe the answer is:
all the rage
'trendy' is the definition.
(thesaurus)
'reasonable skirts silver' is the wordplay.
'reasonable' becomes 'allthere' (I can't justify this - if you can you should believe this answer much more).
'skirts' indicates putting letters inside (skirt can mean to go around).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'allthere' enclosing 'ag' is 'ALL THE RAGE'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for all the rage that I've seen before include "Very popular (informal)" , "Very much in fashion" , "Fashionable" , "most desirable now!" , "The in thing" .)