Duke in hat sees señorita's wiggle (5)
I believe the answer is:
tilde
'senorita's wiggle' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'duke in hat' is the wordplay.
'duke' becomes 'd'.
'in' is an insertion indicator.
'hat' becomes 'tile' (I've seen this before).
'd' going inside 'tile' is 'TILDE'.
'sees' is the link.
Can you help me to learn more?
(Other definitions for tilde that I've seen before include "Accent (used over n) in Spanish and Portuguese" , "senorita lacking one?" , "Accent on some Spanish words" , "Style detail" , "part of Sao Paulo, originally" .)