I think its deer. deer only has 4 letters, and no a.
Venison?
bear deer wolf calf lamb
Flea, deer, wren, rhea, ibex.
dirk
Isle
Peak
kart
Coal
coal
The small fruit that starts with the letter P and is 4 letters long is a plum. They have a stone, or pit inside them.
Bang, boom and snap have 4 letters.