Crawling lover, thin and oddly dreary (7)
I believe the answer is:
leander
'crawling lover' is the definition.
'leander' can be an answer for 'lover' (I've seen this before). I'm not sure about the 'crawling' bit.
'thin and oddly dreary' is the wordplay.
'thin' becomes 'lean' (associated in meaning).
'and' is a charade indicator (letters next to each other).
'oddly' indicates alternate letters (letters in odd-numbered positions).
The alternating letters of 'dreary' are 'der'.
'lean'+'der'='LEANDER'
Can you help me to learn more?
(Other definitions for leander that I've seen before include "Hero's lover; rowing club" , "Ill-fated lover" , "Tragic Greek" , "Hero's hero" , "long-distance swimmer" .)