Emperor appears in the first type of suit (5)
I believe the answer is:
titus
'emperor' is the definition.
(Roman emperor)
'the first type of suit' is the wordplay.
'the first type' becomes 't' (1st letter of 'type').
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'suit' is an anagram of 'itus'.
't'+'itus'='TITUS'
'appears in' is the link.
(Other definitions for titus that I've seen before include "- Andronicus (Shak.)" , "good book" , "recipient of holy letter" , "Only part of Shakespeare play" , "-- Groan, novel by Mervyn Peake" .)