Pleasant beer brewed with algae? (9)
I believe the answer is:
agreeable
'pleasant' is the definition.
(similar in meaning)
'beer brewed with algae?' is the wordplay.
'brewed with' indicates an anagram.
'beer' mixed up with 'algae' can make 'AGREEABLE'.
(Other definitions for agreeable that I've seen before include "delightful" , "sympathetic" , "Willing - nice" , "Pleasant, acceptable" , "In harmony; pleasant" .)