Simple sort of raft hid ragworts (15)
I believe the answer is:
straightforward
'simple' is the definition.
(thesaurus)
'sort of raft hid ragworts' is the wordplay.
'sort of' is an anagram indicator.
'raft'+'hid'+'ragworts'='rafthidragworts'
'rafthidragworts' is an anagram of 'STRAIGHTFORWARD'.
(Other definitions for straightforward that I've seen before include "Easy to understand" , "That's simple" , "Uncomplicated" , "Frank" , "Honest, open" .)