It's clear from the outset - girls love anagrams and silly spoonerisms ... (5)
I believe the answer is:
glass
'it's clear from the outset girls love anagrams' is the definition.
I can't tell whether this definition defines the answer.
'silly spoonerisms' is the wordplay.
I cannot quite see how this works, but
'silly' could be 'ass' and 'ass' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for glass that I've seen before include "(Material used in) mirror" , "Brittle transparent material" , "Something to drink from" , "Transparent solid" , "barometer" .)