What does the cryptic crossword clue "Tree-dweller just too long for narrow opening (4)" mean?

The definition is "narrow opening". The wordplay uses a deletion. SLOT (deletion) = SLOT; definition: "narrow opening" The answer is SLOT.

Tree-dweller just too long for narrow opening (4)

Guardian Cryptic #29686 | 23 Down | 2025-05-05 flower