Well built redhead interrupting research (6)
I believe the answer is:
sturdy
'well built' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives occasionally mean the same thing.
'redhead interrupting research' is the wordplay.
'redhead' becomes 'r' (head letter of 'red').
'interrupting' means one lot of letters goes inside another.
'research' becomes 'study'.
'r' placed into 'study' is 'STURDY'.
Can you help me to learn more?
(Other definitions for sturdy that I've seen before include "Stalwart, stout, tough" , "Strongly and solidly built" , "Strong and solidly built" , "Strong, solid" , "Well-built - strapping" .)