The most common and most likely answer to this crossword clue is the 4 plus 3 letter word COAL TIT
I've seen this crossword clue in Financial Times
C
O
A
L
T
I
T
More clues leading to the result COAL TIT
- Colliery with tons for power — this carries a modest bill
- Bird soaring over cape, then height almost halved
- Key I placed in bed for singer
- Bird identified by lieutenant, one wearing outdoor garment
- Small bird needs tail bent when in bed
- Flier left in jacket: latest offerings from Balti restaurant
- Bird wagging tail in bed
- Blackbird’s a flier?
- ‘Layer’ carrying leaves initially, it being a bird
- Place cover over unsteadily lit bird
Buddy explains!
The straight part
We know that "singer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case singer = coal tit.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.