The Moor gets too involved about the underworld (7)
I believe the answer is:
othello
'the moor' is the definition.
(I've seen this before)
'too involved about the underworld' is the wordplay.
'involved' indicates anagramming the letters (involved can mean confusing or complex).
'about' is an insertion indicator.
'the underworld' becomes 'hell' (synonyms).
'too' is an anagram of 'oto'.
'oto' enclosing 'hell' is 'OTHELLO'.
'gets' acts as a link.
(Other definitions for othello that I've seen before include "He opposed the Turkish" , "Hello to Shakespeare's tragic hero" , "Shakespeare's tragic Moor who killed his wife" , "Moorish gentleman" , "Shakespearean Moor" .)