What may cause danger if tossed by first to enter? (7)
I believe the answer is:
grenade
'tossed by first to enter?' is the definition.
I can't tell whether this defines the answer.
'what may cause danger' is the wordplay.
I cannot quite see how this works, but
an anagram of 'danger' is 'grenad' which is within the answer.
A single letter 'e' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'if' is the link.
Can you help me to learn more?
(Other definitions for grenade that I've seen before include "Small bomb thrown by hand" , "Small hand missile" , "Handy bomb" , "Missile thrown" , "Hand-thrown bomb" .)